JPH0828603A - Inwardly extending dram brake device - Google Patents

Abstract

PURPOSE:To improve assembling easiness by reducing the number of parts and prevent a brake shoe from floating up. CONSTITUTION:A coil spring 8 for energizing a brake shoe 5 in its return direction and positioning it is wound up around an adjustment bolt 7 with its one end brought in contact with a flange 7c and its other end with a member facing thereto. Thus, a stable attachment state can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal expansion type drum brake device.

[0002]

2. Description of the Related Art Japanese Unexamined Utility Model Publication No. 62-59332 and the like can be cited as an example of an internal expansion type drum brake device of this type.

The inner expansion type drum brake device is provided in a base plate having a hub shaft fitting hole in the center and a mounting hole for a vehicle body at the end, and in a substantially intermediate part between the both holes of the base plate. A substantially circular shoe and a fixed shaft that is coaxially passed through the crank; and a compression spring that fits around the fixed shaft and has one end in contact with the head of the fixed shaft and the other end in pressure contact with the crank. Shoe
One end is rotatably supported by the fixed shaft between the crank and the base plate, the other end has a joint with the crank, and the rotation of the crank increases the diameter of the substantially circular shoe. The adjusting bolt can adjust the return position of the shoe when not operating. In such an inner expansion type drum brake device, the loosening of the adjusting bolt is prevented by urging the bolt with a spring material, or a double nut is used with a nut material. Further, in order to prevent the brake shoe from floating from the substrate, a compression spring is attached to urge the brake shoe, or the brake shoe is restrained by a holding plate.

[0004]

The above-mentioned internal expansion type drum brake device has the following problems.

<B> The conventional inner expansion type drum brake device is provided with a spring member for urging the brake shoe in the returning direction and a spring member for preventing the adjustment bolt from loosening. In addition, the adjustment bolt is prevented from being loosened by the double nut formed by the screw portion of the back plate and the screw portion of the nut member. Therefore, a spring for biasing the brake shoe in the returning direction and a spring or nut member for preventing the adjustment bolt from loosening are separately required.

<B> In order to prevent the brake shoe from floating from the back plate, a compression spring or a pressing plate, which is an individual member, is required separately.

<C> Since the number of parts constituting the inner expansion type drum brake device increases due to the above-mentioned <A> and <B>, the assembly thereof becomes complicated.

<D> When the return position of the brake shoe is adjusted with the adjusting bolt, the urging force of the spring for urging the brake shoe to the return position changes, so that the durability of the spring becomes a problem. Further, when the biasing force of the spring increases, the initial loss during brake operation also increases, leading to a reduction in the braking force.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the number of parts as a whole to improve the assemblability and to raise the brake shoe. (EN) An inner expansion type drum brake device capable of preventing the occurrence of a slip.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a brake shoe is rotatably arranged on a back plate fixed to a vehicle body, and an engaging portion extended from the brake shoe and a locking portion formed on the back plate. In the inner expansion type drum brake device in which the distance between the brake shoe and the brake shoe is adjusted by an adjustment bolt, and the brake shoe is biased in the return direction by a coil spring, the coil spring is wound around the adjustment bolt and one end is adjusted. An inner expansion type drum brake device, characterized in that a collar portion formed on a bolt is in contact with a member facing the other end, respectively. Further, in the above-mentioned inner expansion type drum brake device, the coil spring is locked so as to prevent rotation of the adjusting bolt in the returning direction, which is an inner expansion type drum brake device. Further, in each of the inner expansion type drum brake devices described above, the engaging portion of the brake shoe and the locking portion of the back plate suppress the lifting of the brake shoe from the back plate via the adjustment bolt,
An inner expansion type drum brake device, characterized in that a brake shoe is guided in an expansion direction.

[0011]

Embodiment 1 An embodiment of the present invention will be described below with reference to FIGS.

<B> Outline of Inner Expansion Type Drum Brake Device The inner expansion type drum brake device is, for example, highly braking against one direction rotation (clockwise in FIG. 1) of the brake drum 1 as shown in FIG. Take an example of a uni-servo type internal expansion type drum brake device that is effective. The inner expansion type drum brake device is fixed to the vehicle body by the back plate 2, and its braking operation is performed by pulling the brake lever 3 by a mechanical operation means such as a cable or a link (not shown).
The cam 4 fixedly attached to the brake shoe 5 rotates to open one end of the brake shoe 5 so that the brake shoe 5 slides on the brake drum 1.

Back Plate (FIG. 1) The back plate 2 has mounting holes 2a and 2b and is fixed to the vehicle body by bolting or the like. The back plate 2 is also provided with a cylindrical anchor portion 2c. The anchor portion 2c has an outer peripheral side surface that receives the braking torque transmitted to the brake shoe 5, and an inner peripheral side surface that pivotally supports the cam 4. In addition,
The anchor part 2c is caulked from the back plate 2 and is welded,
It may be fixed by screwing or the like, or may be integrally formed from the back plate 2.

Cam (FIG. 1) The cam 4 is disposed by being fitted into the anchor portion 2c, and the brake lever 3 is fixed to the outside (or the back side) by screwing or the like. Also, the sticking of the brake lever-3 is caused by welding,
It is also possible to use caulking, press fitting, and clips.

Brake Shoe (FIG. 1) The brake shoe 5 is formed in a substantially circular single shape and has a rim portion 5a substantially parallel to the inner peripheral surface of the brake drum 1 and an inner peripheral side substantially perpendicular to the rim portion 5a. It comprises a web portion 5b extending to and a friction material 5c fixed to the outer peripheral surface of the rim portion 5a. The rim portion 5a and the friction material 5c are fixed to each other by means of adhesion, riveting, a combination of both, or a friction material 5c.
There is a method of integrally molding with the rim portion 5a. The brake shoe 5 has an L-shaped cross section in which the rim portion 5a and the web portion 5b are continuous, but individual parts are welded to the rim portion 5a by welding the web portion 5b to the T-shaped cross section. It may be formed or may be formed by welding two or more web portions 5b in parallel to the rim portion 5a. Further, the web portion 5b and the friction material 5c are each divided into two pieces, but they may be continuous one piece or may be divided into three or more pieces.

An end portion of the web portion (FIG. 1) An anchor hole 5d that engages with an outer peripheral side surface of the anchor portion 2c is provided at one end of the brake shoe 5, and a cam 4 is provided at the other end.
An abutting portion 5e that abuts against is formed.

Intermediate part of the web part (FIG. 1) The web part 5b has a notch 5f formed on the inner peripheral side in the middle thereof, and a pair of left and right web parts are formed on the rim part 5a with a space therebetween. You may weld it. When the friction material 5c wears and the amount of brake operation (expansion) increases, the elastic limit of the brake shoe 5 is exceeded, so the notch 5f or the rim portion 5a near the division is permanently deformed, and the brake that follows wear is braked. Hold diameter.

Therefore, normally, the force for operating (spreading) the brake is always light and constant. Further, it is not necessary to add any component to secure the returning position of the brake shoe 5 that follows the wear. When there is a concern that the cutouts 5f may reduce the strength, a stiffener may be fixed to the rim portions 5a to reinforce the rim portions 5a near the cutouts 5f. That is, the stiffener is welded inside the rim portion 5a near the notch 5f.

<B> Holding part (FIGS. 1, 2 and 3) The holding part 6 is a box type in which a member composed of a front side surface, a right side surface, a left side surface and a bottom surface is formed on a part of the back plate 2, and is an adjusting bolt. It houses 7 mag. An introduction hole 6a having a diameter larger than that of the head portion 7a of the adjustment bolt 7 is formed on the front side surface of the holding portion 6.
A guide groove 6b is formed extending continuously from a to the left side surface and slightly wider than the diameter of the neck lower portion 7b of the adjusting bolt 7. Further, a locking portion 6c is formed on the right side surface of the holding portion 6 so that the tip of the adjusting bolt 7 abuts. Although the above-mentioned holding portion 6 is formed on the outer periphery of the brake drum 1 on the lower side in the figure, the invention is not limited to this. May be.

<C> Engaging Arm (FIGS. 1, 4, and 5) The engaging arm 9 extends from the brake shoe 5 so as to bypass the opening side of the brake drum 1. In this case, as shown in FIG. 1, the rivet 10 is a component separate from the brake shoe 5,
It may be fixed by bolting, welding or the like, but may be integrally formed from the brake shoe 5. The tip of the engaging arm 9 is bent in parallel with the locking portion 6c of the holding portion 6 to form an engaging portion 9a. Further, the engaging portion 9a is provided with a female screw portion 9b.

<D> Adjustment bolts (FIGS. 1 and 5) The adjustment bolts 7 are arranged from the left side in FIG.
It is composed of a collar portion 7c and a screw portion 7d. The head portion 7a is formed with a cross-shaped or one-shaped groove or a hexagonal outer shape so that it can be rotated by a tool such as a screwdriver or a spanner. A coil spring 8 is contracted between the flange portion 7c of the adjustment bolt 7 and the left side surface of the holding portion 6, and the adjustment bolt 7 is biased rightward so that the tip of the adjustment bolt 7 contacts the locking portion 6c. I am in contact. The threaded portion 7d of the adjusting bolt 7 is the engagement portion 9 of the engagement arm 9.
It is screwed into the threaded portion 9b to be drilled in a. Then, by rotating the adjusting bolt 7, the interval between the locking portion 6c of the holding portion 6 and the engaging portion 9a of the engaging arm 9 is widened or narrowed to adjust the return position of the brake shoe 5. . The adjustment bolt 7 is attached to the holding portion 6 by screwing the adjustment bolt 7 onto an engaging arm 9 that is substantially integral with the brake shoe 5, and attaching a coil spring 8 to the lower neck portion 7b of the adjustment bolt 7. In the state
From the inside of the holding portion 6, insert the head portion 7a of the adjusting bolt 7
It is carried out by pulling it out from a and sliding it into the guide groove 6b.
Further, the adjusting bolt 7 having the coil spring 8 mounted therein is arranged such that the head portion 7a of the adjusting bolt 7 is brought out from the introduction hole 6a from the inside of the holding portion 6 and slid in the guide groove 6b, and then the adjusting bolt 7 is placed. May be screwed onto the engagement arm 9.

[0022]

The operation of the internal expansion type drum brake device will be described below with reference to the drawings.

<A> Prevention of adjustment bolt loosening (see FIG. 1) Non-operating state When the inner expansion type drum brake device is in the non-operating state, between the flange portion 7c of the adjusting bolt 7 and the left side surface of the holding portion 6. Since the coil spring 8 contracted to urge the adjusting bolt 7 to the right to bring the tip of the adjusting bolt 7 into contact with the locking portion 6c of the holding portion 6, the adjusting bolt 7 does not loosen. .

Operating State When the internal expansion drum brake device is operating, when the brake lever 3 is pulled and the cam 4 is rotated, the notch 5f is formed.
Since the brake shoe 5 on the more right side expands and the entire brake shoe 5 moves to the left, the adjusting bolt 7 screwed into the engaging arm 9 also moves to the left while contracting the coil spring 8 to move the adjusting bolt. The tip of 7 is separated from the locking portion 6c. Then, the coil spring 8 is attached to the threaded portion between the adjusting bolt 7 and the engaging portion 9a.
The adjusting bolt 7 tends to be screwed out to the right from the engaging portion 9a. The structure is such that the adjusting bolt 7 is prevented from being unscrewed (loosened) by the screwing direction of the adjusting bolt 7 and the winding direction of the coil spring 8. That is, when the screw portion 7d of the adjusting bolt 7 is a right-hand screw, the adjusting bolt 7
Tries to be screwed out from the engaging portion 9a by rotating clockwise (as viewed from the head 7a side of the adjusting bolt 7), but by winding the coil spring 8 leftward, the edge of the coil spring 8 end Can be hooked on the flange portion 7c of the adjustment bolt 7 and the left side surface of the holding portion 6 to prevent the adjustment bolt 7 from rotating rightward. It should be noted that the screw portion 7d of the adjusting bolt 7 may be left-handed and the coil spring 8 may be right-handed. In addition, coil spring 8
If the friction coefficient is increased by forming unevenness or the like on the abutting surfaces of the collar portion 7c and the holding portion 6, it will be more easily locked.

<B> Prevention of lifting of brake shoe (see FIGS. 1, 2 and 5) The brake shoe 5 slides in parallel with the back plate 2 along with the adjusting bolt 7, and the neck portion 7b of the adjusting bolt 7 is Since it is guided in the sliding direction by the guide groove 6b of the holding portion 6, the lift of the brake shoe 5 from the back plate 2 can be prevented. That is, the brake shoe 5 is integrally connected to the engagement arm 9 by the rivet 10 and the like, and the engagement portion 9a of the engagement arm 9 is screwed to the screw portion 7d of the adjustment bolt 7, so that the brake shoe 5 is adjusted. The structure is up to the screw 7. Therefore, the adjusting bolt 7 has its neck lower portion 7b constrained by the guide groove 6b of the holding portion 6 in the floating direction of the brake shoe 5.

[0026]

[Embodiment 2] FIG. 6 is Embodiment 2 in which the structure and attachment of the adjusting bolt 7 are different. That is, in the configuration of the adjusting bolt 7 according to the second embodiment, the head 7a, the head flange 7e, the stepped screw portion 7f, the flanged nut member 7g, and the stepped screw portion 7f are arranged from the right side.
Is screwed on. Assembling the adjusting bolt 7 to the inner expansion type drum brake device is performed by screwing the large diameter portion of the stepped screw portion 7f of the adjusting bolt 7 into the engaging portion 9a of the engaging arm 9 and then attaching the nut member with the flange portion. 7 g is screwed into the small diameter portion and locked at the stepped surface with the large diameter portion. Then, the coil spring 8 is contracted outside the small diameter portion, and the head portion 7a of the adjusting bolt 7 is housed in the holding portion 6 by projecting from the inside of the holding portion 6 to the outside from the introduction hole 6a. In this embodiment, the hole or groove formed in the holding portion 6 is only the introduction hole 6a, and normally the head flange 7e and the locking portion 6 are provided.
Since c (around the introduction hole) abuts and closes the introduction hole 6a, waterproof and dustproof effects are obtained.

[0027]

Third Embodiment FIG. 7 shows a third embodiment, which is different from the first and second embodiments in the structure and attachment of the adjusting bolt 7. Example 3
The adjusting bolt 7 in is a head portion 7 with a collar portion that also serves as a collar portion.
h, the engaging arm 9 on the stepped surface between the neck lower portion 7b and the screw portion 7d.
The engaging portion 9a is locked, and the screw portion 7d is screwed into the locking portion 6c of the holding portion 6. In the case of this embodiment, the brake shoe 5 can be prevented from rising from the back plate 2 by the guide groove 9b of the engaging portion 9a being guided by the neck lower portion 7b of the adjusting bolt 7.

[0028]

Since the present invention is as described above, the following effects can be obtained.

<A> Since the coil spring for urging the brake shoe in the returning direction also has the function of preventing the adjustment bolt from loosening, the number of parts constituting the inner expansion type drum brake device can be reduced.

<B> Since the engaging portion of the brake shoe and the engaging portion of the back plate suppress the lifting of the brake shoe from the back plate through the adjusting bolt and guide the brake shoe in the expanding direction, It is possible to prevent the brake shoe from rising from the back plate without using separate parts.

<C> Since the number of parts is reduced by the above-mentioned <A> and <B>, the assembling property of the inner expansion type drum brake device is improved.

<D> Even if the return position of the brake shoe is adjusted with the adjusting bolt, the urging force of the coil spring does not change,
The durability of the coil spring is improved. Further, since the urging force of the coil spring does not change, the stable braking force can be obtained without increasing the initial loss during the brake operation. Furthermore,
Since the coil spring is wound around the adjusting bolt, a stable mounting state can be secured.

[Brief description of drawings]

FIG. 1 is a front view of an internal expansion type drum brake device.

FIG. 2 is a left side view of a holding portion of the inner expansion type drum brake device according to the first embodiment.

FIG. 3 is a front view of a holding portion of the inner expansion type drum brake device according to the first embodiment.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view of a holding portion of the inner expansion type drum brake device according to the first embodiment.

FIG. 6 is a sectional view of another embodiment of the holding portion.

FIG. 7 is a cross-sectional view of yet another embodiment of the holding portion.

[Explanation of symbols]

 1 ... Brake drum 7f ... Stepped screw part 2 ... Back plate 7g ... Collar part nut member 2a, b ... Mounting hole 7h ... Collar part head 3 ... Brake lever 8 ... Coil spring 4 ... Cam 9 ... Engaging arm 5 ... Brake shoe 9a ... Engagement part 5a ... Rim part 9b ... Female thread part 5b ... Web part 10 ... Rivet 5c ... Friction material 5d ... Anchor hole 5e ... Abutment part 5f ... Notch 6 ... Holding part 6a ... Introduction hole 6b ... Guide groove 6c ... Locking part 7 ... Adjustment bolt 7a ... Head 7b ... Lower neck 7c ... Collar part 7d ... Screw part 7e ... Head flange

Claims (3)

[Claims] 1. A brake shoe is rotatably arranged on a back plate fixed to a vehicle body, and a gap between an engaging portion extending from the brake shoe and a locking portion formed on the back plate is adjusted by an adjusting bolt. Together with the inner expansion type drum brake device in which the brake shoe is biased and positioned by a coil spring in the returning direction, the coil spring is wound around the adjustment bolt, and one end is formed on the flange portion formed on the adjustment bolt, An inner expansion type drum brake device, characterized in that the other end is in contact with a member facing the other end, respectively. 2. The inner expansion type drum brake device according to claim 1, wherein the coil spring is locked so as to prevent rotation of the adjusting bolt in the returning direction. Drum brake device. 3. The inner expansion type drum brake device according to claim 1, wherein the engaging portion of the brake shoe and the engaging portion of the back plate are separated from the back plate of the brake shoe via the adjustment bolt. The internal expansion type drum brake device is characterized in that the brake shoe is restrained from rising and the brake shoe is guided in the expansion direction.